New Zealand consumers face a long wait before they know if they can get a weight-loss pill which has been approved in the United States. It is the first to be given the legislative nod by US health regulators in 13 years.

Anti-obesity pill Belviq was designed to block appetite signals in the brain, making patients feel fuller with smaller amounts of food.

Manufacturer Arena Pharmaceutical is targeting adults with a body mass index (BMI) of 30 or greater, or those with a BMI of 27 who also have high blood pressure, type-two diabetes or high cholesterol.

BMI estimates how much body fat a person has by dividing weight by height squared. A healthy BMI score is between 18.5 and 26.

In the United States, the Federal Drug Administration (FDA) reviewed the safety of the drug in three trials lasting between 52 and 104 weeks. It involved more than 8000 overweight people.

Those who took Belviq for up to 12 months lost three to four percent more of their body weight than those who took a placebo. Possible side effects included migraines, depression and memory lapses.

Medsafe has not received an application for consent to distribute Belviq in New Zealand, Ministry of Health media advisor Anna Chalmers said.

Before a medicine is approved here an application must be lodged outlining its safety, quality and efficacy.

How long it took to be approved depended on how quickly the applicant addressed deficiencies or concerns raised, she said.

It would then have to be considered for funding by Pharmac, the government drug-buying agency.

Pharmac have received no such request, communications manager Simon England said.

The main weight-loss pills on sale in New Zealand are Duromine, an appetite suppressant, and Xenical.Belviq is expected to launch in the United States next year.

It was rejected by the FDA in 2010, when studies showed it led to the development of tumours in animals, but further studies showed it did not have the same effect on humans.

Belviq was the first weight loss approved since Xenical, which works by blocking 30 per cent of fat eaten.

Although Xenical is still on the US market, reported side effects have included flatulence, abdominal pain and liver injury.

FDA has pulled a number of weight-loss pills from the market because of serious health implications - such as damaged heart valves, lung problems, threats of heart attacks and strokes, kidney stones and psychosis.Belviq did not pose those risks, the FDA said.